7520e printer problem

Printer has been working prior to today. I just turned on on and on the display a message came up " Missing or Failed Print head" I have powered down waited 1 min. , Unplug, checked paper try, Remove and reinstalled ike cartiges and still get the same message. I cannot get another display to mavigate with.

What can I do to clear this out. I could not find any information on this in the support area. Could you also send me a full manual that I could not find.